JP3373590B2 - Sliding member - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member having a hard coating on a sliding portion and used for machine parts such as automobile parts and compressor parts. Then, the present invention relates to a sliding member in which titanium is used as a main metal component and further coated with a film made of one or more metal elements and nitrogen and oxygen. 2. Description of the Related Art Sliding parts such as mechanical parts are increasingly used under increasingly severe conditions, such as abrasion resistance and seizure resistance, due to high speed and high output of internal combustion engines and compressors of automobiles. Improvements in dynamic characteristics are expected. Similarly, with respect to cutting tools, it is expected that the sliding characteristics will be improved by increasing the cutting speed. Conventionally, surface treatments such as improvement of abrasion resistance by hard chromium plating, and improvement of seizure resistance by nitridation or molybdenum spraying have been mentioned as measures for improving sliding characteristics. [0003] However, these methods do not provide sufficient sliding properties as a sliding material, and have recently been relatively chemically modified by physical vapor deposition (PVD) or chemical vapor deposition (CVD). A method for producing a stable Cr—N-based or Ti—N-based hard coating has been studied. However, Cr-
Since the N-based coating has a relatively low coating hardness, the coating is liable to wear, and although an attempt has been made to improve this point, sufficient sliding characteristics have not yet been obtained. [0004] Therefore, the development of a film having higher film hardness and excellent sliding characteristics has been desired, and a Ti-N-based film has attracted attention. However, when used as a sliding member such as a machine part, the Ti-N-based coating has a disadvantage that the coating hardness is too high and causes the mating material to be worn. There is also a drawback that "adaptation" is bad. Here, “initial adaptation” means that the surface of a sliding member having roughness due to machining or film formation itself comes into sliding contact with a counterpart material within a short time after the start of sliding, and the surface is fine and smooth. As a result, the contact surface pressure is reduced by increasing the contact area, making it difficult for the lubricating oil film to break, thereby preventing the occurrence of abrasion and seizure. A sliding member coated with a coating having an excessively high hardness, such as a Ti-N-based coating, has a problem in that wear and seizure are likely to occur in the initial stage of sliding due to poor initial adaptation. SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a sliding material coated with a coating containing Ti as a main metal component, such as a sliding material having wear resistance and seizure resistance. An object of the present invention is to solve the above-mentioned problems by coating a hard film having excellent characteristics and good initial conformability. further,
The present applicant has made Japanese Patent Application No. 5-1 to solve the above problem.
No. 20061; titanium, group M (M; one or more metal elements selected from chromium, vanadium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten and aluminum), and nitrogen, Is M / (Ti +
Although a sliding member coated with a film having M) of 1 to 45% has been proposed, an object of the present invention is to further improve the above-described sliding characteristics and reduce wear of a mating material. That is, the sliding member according to the present invention is made of titanium, group M (M; chromium, vanadium, zirconium, niobium, molybdenum, hafnium,
One or two selected from tantalum and tungsten
Or more metal elements), nitrogen and oxygen, the composition ratio of the metal elements is M / (Ti + M) = 1 to 45% in atomic% ratio, and the composition ratio of the gas elements is O / ( N +
O) = 5 to 80% is coated on the substrate. This film has abrasion resistance, seizure resistance, and initial conformability that are lower than those of the TiN film, even though the hardness of the film itself is lower than that of the TiN film, by adding an element of Group M and oxygen to TiN. It was a good one.
Regarding the effects of the elements of group M and oxygen, (a) all decrease the hardness of the TiN film, but the latter has a higher rate of hardness decrease, and (b) the former has a lower coefficient of friction of the TiN film. Although slightly increased, the latter greatly reduces this. (C) In each case, the weight loss due to corrosion of the TiN film in oil is suppressed, but the former is more suppressed.
Since the elements and oxygen in the M group are different due to such influence on physical properties, they are divided into different groups, respectively, and Cr, V, Zr,
Since Nb, Mo, Hf, Ta, and W are all common in the above points, they are included in one group. Here, if the metal element composition ratio of M / (Ti + M) is less than 1%, the effect of improving the initial penetration is small, while if it exceeds 45%, the seizure resistance cannot be improved.
The metal element composition ratio was in the range of 1 to 45%. If the composition ratio O / (N + O) of the gas element is less than 5%, the wear of the mating material increases, whereas if it exceeds 80%, the wear of the coating film itself increases and the sliding characteristics cannot be improved. Various materials such as Fe-based, Al-based and Ti-based materials can be used as the substrate. The thickness of the Ti-M-N-O-based coating is not particularly limited, but is preferably in the range of 1 to 50 m. Similarly, the film roughness is 1 μm in Ra.
The following is preferred. Further, the counterpart material is not particularly limited, and it is possible to use cast iron or steel materials, Cr-plated materials thereof, materials with a thermal spray coating, and the like. Also, the coating of the present invention is formed by PVD or CVD, preferably PVD, on a sufficiently cleaned substrate. The initial conformability of the TiN film is poor.
Since the system coating has poor abrasion resistance, seizure is likely to occur in each case. However, seizure occurs when a Ti-M-N-O system film in which Ti and other metal elements M and N and O coexist. It became difficult to do. In addition, since the initial adaptation was improved, the wear after the adaptation was realized was reduced, and the wear of the mating material was also significantly reduced. Hereinafter, the present invention will be described in detail with reference to Examples in which V is selected as the metal element (M). [0011] The substrate for forming a film used in this embodiment is a high chromium steel (JIS standard SUJ-2). The substrate was subjected to ultrasonic cleaning in a fluorocarbon solution in advance, and a mirror-finished substrate surface was subjected to cathodic arc plasma ion plating by a procedure described below to form a Ti-N-based hard film (comparative example), Ti-V-N Hard Coating (Comparative Example) and Ti-V
A -NO hard coating (Example) was formed. The substrate subjected to ultrasonic cleaning was mounted in a vacuum vessel (chamber) of an ion plating apparatus, and then vacuum was drawn until the pressure in the chamber reached 1.3 × 10 −3 Pa (Pascal). When the degree of vacuum is achieved, the substrate is heated to 300 to 600 ° C. by a heater built in the chamber to release gas components attached or adsorbed on the surface of the substrate.
Cooled down. When the pressure in the chamber becomes 4 × 10 −3 Pa or less, an arc discharge is generated on the surface of a Ti—V alloy target having various compositions as a cathode, and most of Ti and V are ionized. And let it fly out of the target surface. At this time, the jig on which the base is mounted is -700 to
A bias voltage of -1000 V was applied, ionized Ti and V jumping out of the target were attracted to the surface of the substrate and the jig, and these ions collided with the surface to be processed at high speed. An activation treatment of the substrate surface was performed by so-called sputter cleaning in which oxides and the like on the surface to be treated were scraped by the collision of the ionized metal. Thereafter, by introducing a small amount of nitrogen gas into the chamber where the arc discharge is occurring, a portion of ionized Ti and V were combined with the nitrogen gas and deposited as a nitride film on the substrate surface. Thereafter, the flow rate of nitrogen gas is further increased to introduce a flow rate of oxygen gas having a composition ratio of a predetermined gas element to a pressure of about 0.7 to 4.0 Pa, and a bias voltage of 0 to -100 V is applied to the substrate. Thus, a Ti-VNO-based hard coating was formed on the surface of the substrate to a thickness of 1 to 50 µm. In the case of forming the Ti-V-N film of the comparative example, the film was formed in the same manner without introducing oxygen gas.
After the formation of the predetermined film thickness, the temperature in the chamber was cooled to 150 ° C. or less, and then the substrate covered with the film was taken out of the chamber. The hardness of the coating was in the range of Hv = 1000 to 2500. Using the coating obtained by the above method, a sliding test was performed. Example 2 A scuff test was performed using a gray cast iron (FC25) as a mating material using a pin-on-disk friction tester. The scuff test conditions were as follows. Lubrication method: motor oil # 30, oil temperature 80 ° C, oil amount 4
cc / sec Friction speed: 8 m / sec Contact load: Increase from initial 2 MPa to seizure every 1 MPa. Friction time: maintained for 180 seconds under each load Table 1 shows the scuff test results. [Table 1] No V (Ti + V) -1 O (N + O) -1 Scuff value book 1 Ti-V-N-O 13 20 1.9 Departure 2 Ti-V-N-O 45 20 2.0 Description 3 Ti-V-N-O 45 70 2.2 ratio 1 Ti-V-N 45 0 1.8 comparison 2 Ti-N 0 0 1.0 Scuff value is the value when the comparison target Ti-N is 1.0 . No. 1 according to the present invention. 1, 2 and 3 Ti
The V-N-O-based film has a V atom% (hereinafter simply referred to as "V atom%") of 1% for each metal element in the film.
3, 45 and 45%, and the oxygen atom% to the sum of the nitrogen atom and the oxygen atom in the film (hereinafter simply referred to as “oxygen atom%”) is 20, 20 and 70%, respectively. The effects of the atomic percentage of V and oxygen in the coating on the properties of the coating were examined. T without V as a comparative example
A scuff test (baking surface pressure) of 1.0 obtained by performing a scuff test under the same conditions for the i-N-based coating film was compared with the No. 1 of the present invention. The scuff values of the Ti-V-N-O-based coatings 1, 2, and 3 improved about twice or more. In addition, No. 2 and N
o. When the Ti—V—N—O based coating of No. 3 is compared, No. 3 having a large oxygen atom% 3 indicated a high scuff value. Example 3 An abrasion test was performed by using a pin-drum type abrasion tester using gray cast iron (FC25) for the drum. The wear test conditions were as follows. Lubrication method: motor oil # 30, oil temperature 80 ° C, oil amount 8
cc / sec Drum rotation speed: 5 m / sec Contact load: 1.5 MPa Test time: 30 ksec Table 2 shows the wear test results. [Table 2] Pin Drum No V (Ti + V) -1 O (N + O) -1 Abrasion Abrasion Amount 1 Ti-V-N-O 13 20 0.8 0.5 Departure 2 Ti-V-N-O 45 20 0.9 0.4 bright 3 Ti-V -N -O 45 70 0.9 0.3 ratio 1 Ti-V -N 45 0 0.9 0.6 ratio 2 Ti-N 0 0 1.0 1.0 Scuff value is 1 for Ti-N to be compared. 0.0. For comparison, V and oxygen-free T
An abrasion test was performed on the iN-based film and the Ti-VN-based film containing no oxygen under the same conditions as the Ti-VNO-based film. Here, the wear amount of the pin coated with the film was determined from the width of the worn contact surface in the drum rotation direction, and the drum wear amount was determined from the wear depth of the drum. Table 2 shows the characteristics of each of the pin-wear amount and the drum wear amount in the case of the Ti—N-based coating, assuming 1.0. The Ti-VN-0-based coating according to the present invention comprises:
The pin abrasion amount is almost the same as the comparative example, while the drum abrasion amount is significantly reduced as compared with the comparative example. In particular, Ti-V-N-O having 45% V atom% and 70% oxygen atom%
In the system-based coating (No. 3), about 1/3 of the Ti-N-based coating was used.
The amount of wear is suppressed to almost half that of the Ti-V-N-based coating. From the results of the above scuff test and abrasion test, the T-N-based film and the Ti-V-N-based film
The i-V-N-O-based film was found to be a film having excellent seizure resistance, good initial conformability, and capable of suppressing abrasion of a sliding member. As described above, by coating the sliding surface with a film composed of Ti, which is a main metal component, other metal elements, nitrogen and oxygen, the mating material is not worn out. A sliding member with good initial conformability and excellent sliding characteristics such as wear resistance and seizure resistance can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10N 30:06 C10N 30:06 30:08 30:08 40:02 40:02 50:08 50:08 (56) References JP-A-6-145958 (JP, A) JP-A-59-118879 (JP, A) JP-A-61-294659 (JP, A) JP-A-63-186032 (JP, A) JP-A-2-88696 (JP-A-2-88696) JP, A) JP-A-3-188261 (JP, A) JP-A-2-47253 (JP, A) JP-A-3-229882 (JP, A) Patent 3256024 (JP, B2) JP-B-7-74429 (JP, B2) (58) Investigated field (Int. Cl. ⁷ , DB name) C10M 103/06 C10N 10:06-10:12 C10N 30:06-30:08 C10N 40:02 C10N 50:08 F16C 33/12 C23C 14/06-14/08 C23C 26/00

Claims (1)

(57) [Claims 1] Titanium, group M (M; chromium, vanadium, zirconium, niobium, molybdenum, hafnium,
One or two selected from tantalum and tungsten
Or more metal elements), nitrogen and oxygen, the composition ratio of the metal elements is M / (Ti + M) = 1 to 45% in atomic% ratio, and the composition ratio of the gas elements is atomic ratio O / (N + O). )
= 5% to 80% of the base member coated with a coating.